Hong Kong police arrested 48 people, including gamblers and mainland Chinese prostitutes, as a major three-month crackdown against triads and organised crime in the city came to an end.

In one raid early on Wednesday, officers arrested 22 people and seized HK$25,500 (US$3,200) and four arcade game machines. Two accounting books along with game cards were also confiscated.

The 18 men and four women, aged 25 to 56, were picked up when officers raided two residential units on King’s Road and Chun Yeung Street in North Point that were used as gambling dens.

Police said two of the men, aged 28 and 36, were arrested on suspicion of operating the betting establishments, while the others were arrested for gambling. They were being held for questioning.

In Hong Kong, operating a gambling establishment carries a maximum penalty of seven years in jail and a HK$5 million fine. Gambling in an illegal establishment carries a maximum penalty of nine months in jail and a HK$30,000 fine.

Separately, 26 female visitors from mainland China were rounded up in an anti-vice operation jointly mounted by police and immigration officers in Yau Ma Tei on Tuesday. The women were arrested in brothels and hotel rooms on Temple Street, Shanghai Street, Portland Street, Reclamation Street, Jordan Road and Nathan Road when the raids began at about 4pm on Tuesday.

The raids in North Point and Yau Ma Tei were part of a three-month operation code-named “Thunderbolt 18”, which ended on Wednesday.